Fix incorrect RST in cppdocs tensor_basics.rst.txt - #4

Thanks for the fix! This repo is actually generated from the pytorch/docs/cpp folder in the PyTorch repo, so this change wouldn't do anything. I will apply your fixes to the main repo (you would have had to change https://github.com/pytorch/pytorch/blob/master/docs/cpp/source/notes/tensor_basics.rst). I'll also add a note to this repo to clarify this. Thanks again though!